Spin-Flop Phenomenon of Two-Dimensional Frustrated Antiferromagnets without Anisotropy in Spin Space

Nakano, Hiroki; Sakai, Tôru; Hasegawa, Yūko

doi:10.7566/jpsj.83.084709

Cited by 28 publications

(33 citation statements)

References 31 publications

(35 reference statements)

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“…Here, note that the present magnetization jump is a phenomenon different from the increase in the magnetization with a step of ÁS z t ¼ 2 as a characteristic of the spin-nematic phase. [20][21][22] In our recent letter, 18) we reported that the magnetization jump with ÁS z t ¼ 2 found at x ¼ 0:85 is attributed to the spin-flop phenomenon in the isotropic spin space, 6,23) through the observation of an abrupt change in the sublattice magnetization as a function of the magnetization. The jump in the magnetization, as in other examples, is known from various numerical studies of spin-1/2 Heisenberg antiferromagnets on some cluster compounds, 24,25) such as dodecahedron cluster, but its mechanism has not yet been discussed.…”

Section: Magnetization and Phase Diagrammentioning

confidence: 99%

Frustration-Induced Magnetic Properties of the Spin-1/2 Heisenberg Antiferromagnet on the Cairo Pentagon Lattice

2014

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The magnetic phase diagram under a magnetic field of the spin-1/2 Heisenberg antiferromagnet on the Cairo pentagon lattice has been derived from a magnetization process and correlation functions calculated by numerical diagonalization for small clusters with up to 36 sites. The phase transition between two types of 1/3 magnetization states takes place, which continues to the orthogonal dimer state and ferrimagnetic state in the limits of x = 0 and x =¨, respectively, where x is the ratio between two types of nearest-neighbor exchange interactions, in the absence of a magnetic field. A peculiar magnetization jump has been found at the lower-or higher-field edge of the 1/3 plateau, when x is larger or smaller than its critical value of ³0.8, respectively. The temperature dependence of the specific heat shows a doublepeak structure. Fig. 1. (Color online) (a) Cairo pentagon lattice. (b) The decorated square lattice is topologically equivalent to the Cairo pentagon lattice. In both figures, the square denoted by the (red) dashed line denotes the unit cell.

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Section: Magnetization and Phase Diagrammentioning

confidence: 99%

Frustration-Induced Magnetic Properties of the Spin-1/2 Heisenberg Antiferromagnet on the Cairo Pentagon Lattice

2014

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“…11,[47][48][49] Regarding the existence or the absence of the degeneracy, this behavior is different from the magnetization jump observed in square-kagome-lattice and Cairo-pentagon-lattice antiferromagnets, and so on. [50][51][52][53] Although this behavior occurs irrespective of the value of S, the skip of m at the jump gradually decreases as S is increased. Around m = (9S − 2)/(9S) near the jump for S = 1, 3/2, 2, and 5/2, a region where the gradient of the magnetization process seems small may exist, although the behavior is very faint.…”

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confidence: 97%

“…In the case of S = 1/2, the m = 1/3 state of several frustrated systems shows an interesting phase transition between the ferrimagnetic state and another state accompanied by a novel spin-flop phenomenon. 27,[50][51][52][53]62 One of the cases is when the kagome lattice is distorted to the √ 3 × √ 3 type. 27 Future studies taking this distortion into account could help us to more clearly estabish the relationship between the nine-site structure pointed out in Ref.…”

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Magnetization Process of the Spin-S Kagome-Lattice Heisenberg Antiferromagnet

Nakano

Sakai

2015

J. Phys. Soc. Jpn.

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The magnetization process of the spin-S Heisenberg antiferromagnet on the kagome lattice is studied by the numerical-diagonalization method. Our numerical-diagonalization data for small finite-size clusters with S = 1, 3/2, 2, and 5/2 suggest that a magnetization plateau appears at one-third of the height of the saturation in the magnetization process irrespective of S. We discuss the S dependences of the edge fields and the width of the plateau in comparison with recent results obtained by real-space perturbation theory.Frustrated spin systems have attracted much attention from many condensed-matter physicists. One of the fascinating systems among them is the kagome-lattice Heisenberg antiferromagnet. Unfortunately, our understanding of this system is still far from complete in spite of many experimental and theoretical studies. In the S = 1/2 system, in particular, discoveries of several realistic materials such as herbertsmithite, 1, 2 volborthite, 3, 4 and vesignieite 5, 6 have accelerated theoretical studies. 7-29 However, there remain some unresolved issues; one of them is the spin-gap problem of whether the spin excitation above the singlet ground state is gapped or gapless.On the other hand, fewer studies on S > 1/2 cases have been carried out. As candidate S = 1 kagome-lattice systems, m-MPYNM·BF 4 , 30, 31, 33 and KV 3 Ge 2 O 9 34 are known. Theoretical studies 9, 35-39 for the S = 1 case are also limited. Studies on the S > 1 cases have only started recently; candidate kagome-lattice systems of Cs 2 Mn 3 LiF 12 40 for S = 2 and NaBa 2 Mn 3 F 11 41 for S = 5/2 have been reported, together with theoretical studies 42-44 as well as an analysis based on the semiclassical limit. 13 Under these circumstances, then, we are faced with a question: do any systematic behaviors exist in the spin-S kagome-lattice Heisenberg antiferromagnet under magnetic fields? The purpose of this letter is to extract such systematic behavior of the magnetization processes of this model for various S by numerical-diagonalization calculations that are unbiased against approximations. With the same motivation, Zhitomirsky recently investigated the frustrated Heisenberg model under magnetic fields by real-space perturbation theory taking into account fluctuations around a classical configuration. 44 He found that in the magnetization process of the kagome-lattice antiferromagnet, the so-called uud state is stable at one-third of the height of the saturation, at which a magnetization plateau appears irrespective of the value of S. He also derived an expression for the 1/S expansion for both the edge fields of this height. The comparison between the * E-mail: hnakano@sci.u-hyogo.ac.jp † present numerical-diagonalization results and the results from real-space perturbation theory should contribute to our understanding of the frustration effect in the kagome-lattice antiferromagnet.The Hamiltonian that we study in this research is given by H = H 0 + H Zeeman , whereandHere, S i denotes the spin operator at site i, where the sites are th...

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“…5. The size dependence of h 2 is [3][4][5], and the results for J2/J1 = 1.04 are the additional data. The critical fields h1, h2, h3, and h4 are indicated by the red arrows.…”

Section: Square Kagome Lattice and The Exact Diagonalizationmentioning

confidence: 99%

Metamagnetic jump in the spin- 12 antiferromagnetic Heisenberg model on the square kagome lattice

2018

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The magnetization process of the spin-1/2 antiferromagnetic Heisenberg model on twodimensional square-kagome lattice is studied theoretically. The metamagnetic jumps exist in the magnetization process at the higher edge of the 1/3 and 2/3 plateaus. The parameter-dependencies of the critical field and the magnitude of the magnetization jump at the higher edge of the 1/3 plateau are obtained by using the approximated state in the unit cell and compared with the numerical results of the exact diagonalization of 42 sites.

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Spin-Flop Phenomenon of Two-Dimensional Frustrated Antiferromagnets without Anisotropy in Spin Space

Cited by 28 publications

References 31 publications

Frustration-Induced Magnetic Properties of the Spin-1/2 Heisenberg Antiferromagnet on the Cairo Pentagon Lattice

Frustration-Induced Magnetic Properties of the Spin-1/2 Heisenberg Antiferromagnet on the Cairo Pentagon Lattice

Magnetization Process of the Spin-S Kagome-Lattice Heisenberg Antiferromagnet

Metamagnetic jump in the spin- 12 antiferromagnetic Heisenberg model on the square kagome lattice

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